Ethylene gas, as a growth promoter, generated from agricultural products such as fruits is known to have an effect of enhancing maturing of the agricultural products. In particular, as to apples, a research reported that the generated ethylene gas causes the drop of fruits from branches.
In addition, the agricultural products generate ethylene gas even after harvesting. In a space of high concentration of ethylene gas, the maturing of the agricultural products is significantly accelerated, thus resulting in rotting.
It is consequently desirable to eliminate ethylene gas in order to prevent the agricultural products from dropping and to keep their freshness even after harvesting.
The related art conducts the removal of ethylene gas through the use of a multilayer-structure plastic film having a layer containing a photocatalyst as a surface layer (for example, refer to Japanese Patent Application Laid-Open (JP-A) No. 2007-307884). However, a portion of bottom surface side of an agricultural product wrapped therearound by the plastic film (to the base material side on which the agricultural product is placed) is difficult to be irradiated with the light for activating the photocatalyst, and thus there raises a problem of accelerating the maturing at the bottom surface side of the agricultural product, resulting in rotting. In addition, since the agricultural, product wrapped by the plastic film is hermetically sealed, the ethylene gas fills the space near the fruit to enhance the maturing.
Furthermore, there is provided a method for efficiently and surely decomposing or removing the ethylene gas by detecting the quantity of ethylene gas and by varying the amount of irradiation of ultraviolet (UV) light based on the quantity of ethylene gas, thus optimizing the active mass of the photocatalyst means (for example, refer to JP-A No. 2002-204653). Although the method can efficiently and surely perform decomposition and removal of the ethylene gas from the harvested agricultural products, the method has a problem of failing in preventing the fruit before harvesting from dropping.
With such a background, there has been an increasing need for a technology which can suppress the ethylene gas concentration before and after the harvesting of agricultural products.